Fix reroutes lost when dropping output links on reroute (#820)

Blocks attempts to drag links from an output onto a reroute in any of
the links.

src/canvas/FloatingRenderLink.ts

@@ -96,6 +96,15 @@ export class FloatingRenderLink implements RenderLink {
     this.fromPos = fromReroute.pos
   }
 
+  canConnectToReroute(reroute: Reroute): boolean {
+    if (this.toType === "input") {
+      if (reroute.origin_id === this.inputNode?.id) return false
+    } else {
+      if (reroute.origin_id === this.outputNode?.id) return false
+    }
+    return true
+  }
+
   connectToInput(node: LGraphNode, input: INodeInputSlot, _events?: LinkConnectorEventTarget): void {
     const floatingLink = this.link
     floatingLink.target_id = node.id

src/canvas/LinkConnector.ts

@@ -538,6 +538,7 @@ export class LinkConnector {
 
       for (const renderLink of this.renderLinks) {
         if (renderLink.toType !== "output") continue
+        if (!renderLink.canConnectToReroute(reroute)) continue
         if (isValidConnectionToOutput(renderLink, node, output)) return true
       }
     }

src/canvas/MovingRenderLink.ts

@@ -86,6 +86,15 @@ export class MovingRenderLink implements RenderLink {
     this.fromSlotIndex = this.toType === "input" ? outputIndex : inputIndex
   }
 
+  canConnectToReroute(reroute: Reroute): boolean {
+    if (this.toType === "input") {
+      if (reroute.origin_id === this.inputNode.id) return false
+    } else {
+      if (reroute.origin_id === this.outputNode.id) return false
+    }
+    return true
+  }
+
   connectToInput(inputNode: LGraphNode, input: INodeInputSlot, events: LinkConnectorEventTarget): LLink | null | undefined {
     if (input === this.inputSlot) return
 

src/canvas/ToOutputRenderLink.ts

@@ -31,6 +31,11 @@ export class ToOutputRenderLink implements RenderLink {
       : this.node.getInputPos(inputIndex)
   }
 
+  canConnectToReroute(reroute: Reroute): boolean {
+    if (reroute.origin_id === this.node.id) return false
+    return true
+  }
+
   connectToOutput(node: LGraphNode, output: INodeOutputSlot, events: LinkConnectorEventTarget) {
     const { node: inputNode, fromSlot, fromReroute } = this
     if (inputNode) return